Spinning solution comprising viscose and modified polyvinyl alcohol and process for preparing fibers therefrom



United States Patent 3,066,107 SPINNING SOLUTION COMPRISING VISCOSE AND MODIFIED PQLYVINYL ALCQHOL AND PROC- ESS 50R PREPARING FIBERS THEREFROM Osamu Fuknshirna and Hirotoshi Kurashige, Kurashiki City, Japan, assignors to Kurashiki Rayon Co., Ltd., Okayama, Japan, a corporation of Japan No Drawing. Filed May 9, 1960, Bar. No. 27,491 Claims priority, application Japan May 11, 1959 3 Claims. (Cl. 26017.4)

This invention relates to the production of regenerated cellulose fibers and is more particularly concerned with the production of regenerated cellulose fibers of improved dyeing properties.

'Heretofore, the dyeability of regenerated cellulose fibers has been such that only those dyestuffs possessed of an affinity for these fibers, such as direct dyes, sulfide dyes, and the like have been used. More recently, however, it has been desired to spin or Weave regenerated cellulose fibers with fibers which are dyeable not only with direct dyes, but also with acid dyes, or cellitone dyes, such as nylon, cellulose acetate, and the like. There is thus an important need for regenerated cellulose fibers having an improved dyeability with respect to these dyes.

Studies have already been made as revealed bylapanese Patent No. 23 6,202 on a method of mixing high molecular compounds containing basic nitrogen with viscose mother solution for the purpose of improving the dyeability of the regenerated cellulose fibers. In this case, however, since the viscose mother solution is strongly basic, it reacts with cellulose sodium xanthate, producing insoluble precipitates or coagulations during the operations of mixing and dissolving. Therefore, a process of this type wherein the high molecular compounds containing basic nitrogen are xanthogenized beforehand during the dissolving process (Japanese Patent No. 236,202) are required. However, even when such a process is used, it is necessary to efiect curing in a very short time, and to eifect spinning in about one-half the time heretofore employed with regenerated cellulose fibers. For this reason, the stability of the viscose mother solution was very ditficult to maintain under the conditions found in existing industrial installations for handling regenerated cellulose fibers.

It is an object of this invention to provide a process for producing regenerated cellulose fibers having excellent dyeing properties with respect to dyestuffs for which ordinary regenerated cellulose fibers have substantially no affinity, such as acid dyes, acid mordant dyes, and cellitone dyes, the process making it possible to produce fibers by employing substantially the manufacturing methods already known in the production of regenerated cellulose fibers.

As a result of studies directed to a solution of the above-mentioned difliculties, we have discovered that the dyeability of'regenerated cellulose fibers is markedly irnproved with respect to acid dyes, acid mordant dyes, cellitone dyes, and the like, and that no difliculty is encountered in the stability of the mother solution after mixing, and that regenerated cellulose fibers can be spun under well-known manufacturing conditions, when use is made of a spinning mother solution prepared by dispersing, in the viscose mother solution, emulsions or powders of water-insoluble polyvinyl-alcohol derivatives prepared by subjecting polyvinyl alcohol to etherification by means of epoxy compounds, ethylene-imine, or their derivatives containing basic nitrogen, and to acetalization with aldehydes containing no basic nitrogen.

3,fi65,107 Patented Nov. 27, 1962 Thus, the process of the present invention is characterized by the fact that spinning of the regenerated cellulose fibers is effected in accordance with well-known procedures from a spinning solution prepared by adding to a conventional regenerated cellulose mother solution water-insoluble polyvinyl-alcohol derivatives in emulsified or powder form which have been produced by etherification of polyvinyl alcohol with epoxy compounds containing basic nitrogen, or ethylene-imine, or their derivatives, and acetalization with an aldehyde containing no basic nitrogen.

The viscose mother solution has been found to be very stable, although the reason for the stability is not fully understood, when emulsions or powders of water-insoluble polyvinyl-alcohol derivatives of the character described above are added to the viscose mother solution in the quantity needed for the desired improvement in the dyeability of the fibers, this stability being exhibited during the steps of mixing and dispersing, whereby perfect mixing is obtained merely by agitation for a very short time, the dispersion being homogeneous and free from difficulties in handling. There is essentially no difference in the curing or ripening time of the resultant mixed viscose mother solution after the mixing and dispersion of the added polyvinyl alcohol derivative in comparison with the conventional practice wherein viscose alone is employed.

It is advantageous to make the diameter of the particles of the water-insoluble polyvinyl-alcohol derivatives containing basic nitrogen to be mixed and dispersed in the viscose mother solution adequate for the steps of filtration and spinning, viz. less than 30 This invention makes it readily possible to produce particles of from about 0.14-0.17 1. to several tens of ,u, and to mix and disperse particles of desirable diameters. The particle size can be varied to meet the requirements of the mechanical properties and dyeability desired in the fibers in accordance with the fineness of the regenerated celluose fibers manufactured.

The content of basic nitrogen in the polymer being more than 0.2%, the proportion of polymer particles mixed with the viscose mother solution is suitably from about 0.05% to 2% by weight of the cellulose present, measured by the content of the basic nitrogen contained in the polymer. When these proportions are observed, a marked enhancement in the dyeability of the fibers is observed with respect to acid dyes, acid mordant dyes, and cellitone dyes for which heretofore-produced regenerated cellulose fibers have had no aifinity.

In carrying out the acetalization reaction to form the emulsified or powdered polymers suitable for the purpose of this invention, it is generally desirable to employ high speed agitation, and to add various surface-active agents, protective colloids, and the like during the reaction in accordance with conventional emulsification techniques.

In general, various knowmtypes of anionic, non-ionic, and cationic surface-active agents are suitably used. However, an anionic surface-active agent often may form a bond with the basic nitrogen to coagulate the emulsion. Hence, it is preferred to use a non-ionic surface-active agent such as polyoxyethylenedodecyl ether, or a cationic surface-active agent such as dodecyltrimethylammonium chloride. As the protective colloid, water-soluble polymers such as polyvinyl alcohol, partially-saponification products of polyvinyl acetate, gelatin, soluble starch, and amino-acetalized polyvinyl alcohol, are suitably used. In this case, it is also desirable that a non-ionic or cationic polymer be used for the reason referred to in connection with the surface-active agent.

The regenerated cellulose fibers produced by spinning the mixed viscose mother solution prepared in accordance with this invention, can be refined, bleached, and otherwise treated by the same conventional procedures employed in treating regenerated cellulose fibers produced from ordinary viscose mother solutions. The viscose mother solutions to which the above-described polyvinyl alcohol derivatives are added in accordance with this invention are those conventionally used in the viscose process for producing fibers of regenerated cellulose.

The basic nitrogen-containing compounds made use of by the process of this invention are the epoxy compounds obtained by the reaction of epichlorohydrin with secondary amines such as diethyl-amine, dibutyl-amine, dihexylamine, ethyl-cyclohexyl-amine, methyl-butyl-amine, methyl-ethyl-amine, and like alkyl and cycloalkyl amines, and derivatives of compounds having an ethylene-imine ring such as ethylene-imine and compounds obtained by the reaction of ethylene-imine with melamine, and the like.

The aldehydes used for acetalization are any of the various aliphatic or aromatic aldehydes, or their acetals such as formaldehyde, acetaldehyde, propionaldehyde, butylaldehyde, Z-methyl-hexyl-aldehyde, nonylaldehyde, benzaldehyde, chlorobenzaldehyde, naphthaldehyde, salicylaldehyde, meta-methyl-tetra-hydrobenzaldehyde, glyoxal, and the like commonly employed in the acetalization of polyvinyl alcohol.

The invention will be further understood from the following specific examples of practical application. However, it will be understood that these examples are not to be construed as limiting the scope of the present invention in any manner. In these examples, all parts are by weight, unless otherwise indicated.

Example I An aqueous solution containing 3% polyvinyl-alcohol (1300 average degree of polymerization), 1% formaldehyde, and 50% sulfuric acid was heated at 50 C. for one hour with agitation by means of an agitator rotating at 1300 r.p.m. The temperature of the solution was then reduced to 40 C., and an aqueous solution containing 0.5% of a dispersant was slowly added drop-wise in a total amount equal to twice the volume of the initial solution, with continued agitation at 1300 r.p.m. As the reaction proceeded, a pure white finely-divided precipitate of polyvinyl-formal was produced. The degree of acetalization of this fine powder was 67%. The solution was then filtered and the filter cake Washed, and polyvinyl formal in pure white finely divided form was recovered. To 6 g. of this fine powder were added 3 g. of l-dimethylamino-2, 3-epoxypropane, and the mixture was reacted at 120 C. for two hours in a pressure vessel. After the reaction, the finely-divided particles present were separated by filtration and thoroughly washed.

The product thus obtained was a fine powder of a particle size less than 5 in diameter, having very good dyeability, and a basic nitrogen content of 1.5%.

A spinning solution was then prepared by mixing and dispersing, under agitation, this fine powder in a viscose mother solution made up of 8% cellulose and 6% sodium hydroxide, the amount of powder being selected to provide 0.14% nitrogen based on cellulose in the mixture.

This spinning solution was left unattended and cured It was observed that the increase in the amount of dyes absorbed was noticeable in the case of direct dyes, and satisfactory dyeability was manifested with acid dyes, acid mordant dyes, and cellitone dyes. Furthermore, the presence of dyed particles in the fibers after they were dyed was apparent when the fibers were viewed through a microscope.

Example 2 An aqueous solution containing 3% of polyvinyl-alcohol (1500 average degree of polymerization) 1% formaldehyde and 50% sulfuric acid, was heated at 50 C. for 1 hour and a 0.25% water solution of a surface active agent was then added drop-wise very slowly under agitation at the rate of 1500 rpm, in an amount equal in volume to the initial solution.

The thus-treated solution was then filtered and washed, and polyvinyl-formal in finely-divided form was recovered. Ten grams of this polyvinyl-formal were mixed with 2 g. of ethyl-methyl-amino-Z, 3-epoxypropane, and the mixture was heated at 130 C. for 3 hours in a pressure vessel, followed by thorough washing with water and forming the reaction mixture into an emulsion of even finer particle size. The diameters of the particles in this emulsion were from 1 to 2 the amount of basic nitrogen 1.2%, and the degree of acetalization 60%.

This emulsion was then mixed and dispersed under agitation in a viscose mother solution made up of 8% cellulose and 6% sodium hydroxide, making the nitrogen content of the solution 0.1% based on the cellulose.

This spinning solution was cured and left unattended for 50 hours until the Hotten-Rot value reached 9.5, and spinning was carried out by means of the conventional viscose spinning process. When the viscose mother solution was observed under the microscope, nothing unusual was observed regarding the diameter and the condition 0 of dispersion of the particles. After spinning, the fiber for 50 hours until its Hotten-Rot value reached 9.5, and

was refined, bleached, and dyed in accordance with conventional techniques.

The fibers produced as described above in accordance with this invention exhibited entirely satisfactory dye absorption with respect to acid dyes, acid mordant dyes, and cellitone dyes. The fibers absorbed the dyes almost completely as in the case of the fibers described in Example 1.

Example 3 An aqueous solution of 3% polyvinyl-alcohol (1000 average degree of polymerization) 4% benzaldehyde, and 20% sulfuric acid was kept at 50 C. for 60 minutes. The particles suspended in the reaction solution were filtered off and thoroughly washed with Warm water at 40 C. The finely-divided particles thus recovered were dried at 60 C. for 20 hours, and then further pulverized to an average diameter of from 2 to 3,u. Ten grams of this fine powder were mixed with 3 g. of ethylene-imine, and the mixture was heated at C. for 3 hours in a pressure vessel. The product was washed after the reaction,

and a fine powder containing basic nitrogen was obtained.

The amount of basic nitrogen contained in this fine ggigder was 1.5%, and the degree of benzalization was This fine powder was mixed and dispersed with agitation in a viscose mother solution made up of 8% cellulose and 6% sodium hydroxide, making the basic nitrogen content of the solution 0.12% based on the cellulose.

The spinning solution thus produced was left unattended and cured for 55 hours until the Hotten-Rot value reached 9.5, and was then spun into fibers in the same manner as ordinary viscose. The fiber produced by spinning was refined, bleached, and dyed, in conventional manner.

Good results substantially identical with the results described in Example 1 were obtained When these fibers were dyed with direct dyes, acid dyes, acid mordant dyes, and cellitone dyes.

Example 4 An aqueous solution of 4% of polyvinyl-alcohol (1000 average degree of polymerization), 0.5% formaldehyde, 1% glyoxal, and sulfuric acid was heated at 50 C. for 2 hours under agitation at the rate of 1500 rpm. When the reaction was complete, the finely-divided polyvinylacetal which had formed was separated from the solution by filtration and Was washed, and dried at 60 C.

Ten grams of the dried, finely-divided polyvinylacetal were mixed with 3 g. of ethylene-imine, and the mixture was heated at 120 C. for 4 hours in a pressure vessel. After this reaction, the resulting fine powder was thoroughly washed and there was thus obtained a fine powder consisting of polyvinyl acetal containing basic nitrogen. The content of basic nitrogen in this fine powder was 2%, and the degree of acetalization was 60%.

A spinning mother solution was prepared by mixing and dispersing this fine powder with agitation in a viscose mother solution made up of 8% cellulose and 6% sodium hydroxide, to provide a nitrogen content of 0.10% based on the cellulose.

This spinning solution was then cured, after leaving it unattended for 50 hours until a Hotten-Rot value of 9.5 was reached, and was spun into fibers in the same manner as ordinary viscose. The nitrogen content of the spun fibers was 0.1% and the spun fibers were refined and bleached in conventional manner.

Very satisfactory results were obtained when these fibers were dyed not only with direct dyes, but also with acid dyes, acid mordant dyes, and cellitone dyes. The fibers absorbed the dyes ahnost completely.

The surface-active agents or dispersing agents or dispersants, and protective colloids which are suitably employed are, in addition to those mentioned above, any of the many dispersing agents or dispersants and protective colloids known to those skilled in the art of making emulsions or dispersions of polymers. In the foregoing examples, for instance, polyoxyethylenedodecyl ether is suitably used as the dispersant.

It will therefore be understood that, unless otherwise indicated, and as previously mentioned, conventional operations and conventional apparatus are employed in carrying out the process of this invention including conventional mixing and emulsifying units as well as conventional apparatus used in the viscose rayon process. The conditions and the relative relationships set forth in the examples are those preferred in carrying out the process of the invention but it will be understood that other conditions and relationships may be used within the scope of the invention.

It will also be understood that various changes and modifications in addition to those indicated above may be made in the embodiments herein described without departing from the scope of the invention as defined in the appended claims. It is intended, therefore, that all matter contained in the foregoing description shall be interpreted as illustrative only and not as limitative of the invention.

We claim:

1. A process of producing fibers of regenerated cellulose having improved dyeing properties which comprises the steps of adding to a viscose mother solution water-insoluble polyvinyl alcohol derivatives containing basic nitrogen with a particle size below 30 said derivatives being added in an amount such that the basic nitrogen is 0.05% to 2% by weight of the cellulose present, mixing and dispersing said derivatives in said solution, and spinning said fibers from the resultant spinning solution, said polyvinyl alcohol derivatives being the products obtained by acetalization of polyvinyl alcohol with aldehydes free from basic nitrogen followed by etherification of the resultant acetalized polyvinyl alcohol with a member of the group consisting of epoxy compounds obtained by the reaction of epichlorohydrin with secondary amines selected from the group consisting of alkyl amines and cycloalkyl amines, ethylene-imine, and the reaction product of ethylene-imine with melamine.

2. In the production of fibers of regenerated cellulose by the viscose process, the improvement which comprises adding to a viscose mother solution water-insoluble polyvinyl alcohol derivatives containing basic nitrogen with a particle size below 30a, said derivatives being added in an amount such that the basic nitrogen is 0.05% to 2% by weight of the cellulose present, mixing and dispersing said derivatives in said solution, and spinning said fibers from the resultant spinning solution, said polyvinyl alcohol derivatives being the products obtained by acetalization of polyvinyl alcohol with aldehydes free from basic nitrogen followed by etherification of the resultant acetalized polyvinyl alcohol with a member of the group consisting of epoxy compounds obtained by the reaction of epichlorohydrin with secondary amines selected from the group consisting of alkyl amines and cycloalkyl amines, ethylene-imine, and the reaction product of ethylene-imine with melamine.

3. A spinning solution for producing fibers of regenerated cellulose having improved dyeing properties which comprises a viscose mother solution having dispersed therein water-insoluble polyvinyl alcohol derivatives containing basic nitrogen with a particle size of below 30 said derivatives being present in an amount such that the basic nitrogen is 0.05% to 2% by weight of the cellulose present, said polyvinyl alcohol derivatives being the products obtained by acetalization of polyvinyl alcohol with adehydes free from basic nitrogen followed by etherification of the resultant acetalized polyvinyl alcohol with a member of the group consisting of epoxy compounds obtained by the reaction of epichlorohydrin with secondary amines selected from the group consisting of alkyl amines and cycloalkyl amines, ethylene-imine, and the reaction product of ethylene-imine with melamine.

References Cited in the file of this patent UNITED STATES PATENTS 2,092,512 Hermann et al. Sept. 7, 1937 2,906,594 Osugi et al. Sept. 29, 1959 

3. A SPINNING SOLUTION FOR PRODUCING FIBERS OF REGENERATED CELLULOSE HAVING IMPROVED DYEING PROPERTIES WHICH COMPRISES A VISCOSE MOTHER SOLUTION HAVING DISPERSED THEREIN WATER-INSOLUBLE POLYVINYL ALCOHOL DERIVATES CONTAINING BASIC NITROGEN WITH A PARTICLE SIZE OF BELOW 30U, SAID DERIVATIVES BEING PRESENT IN AN AMOUNT SUCH THAT THE BASIC NITROGEN IS 0.05% TO 2% BY WEIGHT OF THE CELLULOSE PRESENT, SAID POLYVINYL ALCOHOL DERIVATIVES BEING THE PRODUCTS OBTAINED BY ACETQALIZATION OF POLYVINYL ALCOHOL WITH ADEHYDES FREE FROM BASIC NITROGEN FOLLOWED BY ETHERIFICATION OF THE RESULTANT ACETALIZED POLYVINYL ALCOHOL WITH A MEMBER OF THE GROUP CONSISTING OF EPOXY COMPOUNDS OBTAINED BY THE REACTION OF EPICHLOROHYDRIN WITH SECONDARY AMINES SELECTED FROM THE GROUP CONSISTING OF ALKYL AMINES AND CYCLOALKYL AMINES, ETHYLENE-IMINE, AND THE REACTION PRODUCT OF ETHYLENE-IMINE WITH MELAMINE. 